Microelectromechanical systems (MEMS) technology has achieved wide popularity in recent years, as it provides a way to make very small mechanical structures and integrate these structures with electrical devices on a single substrate using conventional batch semiconductor processing techniques. One common application of MEMS is the design and manufacture of sensor devices. MEMS sensors are widely used in applications such as automotive, inertial guidance systems, household appliances, game devices, protection systems for a variety of devices, and many other industrial, scientific, and engineering systems. One example of a MEMS sensor is a MEMS angular rate sensor. Alternatively referred to as a “gyroscope”, “vibratory angular rate sensors,” “vibratory rate gyroscopes,” “gyroscope sensor,” or “yaw rate sensor,” an angular rate sensor senses angular speed or velocity around one or more axes.
In vibratory angular rate sensors, an inherent problem is the existence of undesirable interference signals, referred to as a quadrature component or quadrature error. Quadrature error is due to quadrature motion, for example, motion out-of-plane of the proof mass as it oscillates back and forth above the sense electrode. Quadrature motion can occur in vibrating angular rate sensors due to manufacturing imperfections. When present, quadrature motion creates an oscillation on the sense axis that can be confused with Coriolis acceleration and subsequently, the rotation rate. Unfortunately, quadrature error can result in offset error, reduced dynamic range, and increased noise for the device. A large quadrature error can even cause a device to rail so that the sense mass comes into contact with conductive electrodes potentially resulting in collision-related damage, such as a short.